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| The Hello and Goodbye/General chat thread | |
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| Tweet Topic Started: Feb 13 2009, 09:38 PM (157 Views) | |
| Michael Scott | Feb 13 2009, 09:38 PM Post #1 |
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Moderator
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Just talk about anything here. Everyone loves this thread. Hey Everyone!
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| Havok | Feb 13 2009, 09:39 PM Post #2 |
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Hey Guys! How's it going? |
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| Michael Scott | Feb 13 2009, 09:40 PM Post #3 |
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Good. You? |
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| Havok | Feb 13 2009, 09:43 PM Post #4 |
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Eh, I could be better
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| Michael Scott | Feb 13 2009, 09:44 PM Post #5 |
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Yeah. When this forum was advertised, I was actually watching The Simpsons. Now I'm watching King of the Hill. Then Family Guy will be on next. |
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| Havok | Feb 13 2009, 09:48 PM Post #6 |
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Haha, Ohh.. Family Guy
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| wufei526 | Aug 6 2009, 07:05 PM Post #7 |
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Maggie Simpson
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Lamination Some PCBs have trace layers inside the PCB and are called multi-layer PCBs. These are formed by bonding together separately etched thin boards. Drilling Holes, or vias, through a PCB are typically drilled with tiny drill bits made of solid tungsten carbide. The drilling is performed by automated drilling machines with placement controlled by a drill tape or drill file. These computer-generated files are also called numerically controlled drill (NCD) files or "Excellon files". The drill file describes the location and size of each drilled hole. When very small vias are required, drilling with mechanical bits is costly because of high rates of wear and breakage. In this case, the vias may be evaporated by lasers. Laser-drilled vias typically have an inferior surface finish inside the hole. These holes are called micro vias. It is also possible with controlled-depth drilling, laser drilling, or by pre-drilling the individual sheets of the PCB before lamination, to produce holes that connect only some of the copper layers, rather than passing through the entire board. These holes are called blind vias when they connect an internal copper layer to an outer layer, or buried vias when they connect two or more internal copper layers and no outer layers. The walls of the holes, for boards with 2 or more layers, are plated with copper to form plated-through holes that electrically connect the conducting layers of the PCB. For multilayer boards, those with 4 layers or more, drilling typically produces a smear comprised of the bonding agent in the laminate system. Before the holes can be plated through, this smear must be removed by a chemical de-smear process, or by plasma-etch. power leveling, [edit] Exposed conductor plating and coating The places to which components will be mounted are typically plated, because bare copper oxidizes quickly, and therefore is not readily solderable. Traditionally, any exposed copper was plated with solder by hot air solder levelling (HASL). This solder was a tin-lead alloy, however new solder compounds are now used to achieve compliance with the RoHS directive in the EU, which restricts the use of lead. Other platings used are OSP (organic surface protectant), immersion silver (IAg), immersion tin, electroless nickel with immersion gold coating (ENIG), and direct gold. Edge connectors, placed along one edge of some boards, are often gold plated. Electrochemical migration (ECM) is the growth of conductive metal filaments on or in a printed circuit board (PCB) under the influence of a DC voltage bias.[1][2] [edit] Solder resist Areas that should not be soldered to may be covered with a polymer solder resist (solder mask) coating. The solder resist prevents solder from bridging between conductors and thereby creating short circuits. Solder resist also provides some protection from the environment. world of warcraft power leveling, [edit] Screen printing Line art and text may be printed onto the outer surfaces of a PCB by screen printing. When space permits, the screen print text can indicate component designators[1], switch setting requirements, test points, and other features helpful in assembling, testing, and servicing the circuit board. Screen print is also known as the silk screen, or, in one sided PCBs, the red print. Lately some digital printing solutions have been developed to substitute the traditional screen printing process. This technology allows printing variable data onto the PCB, including serialization and barcode information for traceability purposes. wow power level, [edit] Test Unpopulated boards may be subjected to a bare-board test where each circuit connection (as defined in a netlist) is verified as correct on the finished board. For high-volume production, a Bed of nails tester, a fixture or a Rigid needle adapter is used to make contact with copper lands or holes on one or both sides of the board to facilitate testing. A computer will instruct the electrical test unit to send a small amount of current through each contact point on the bed-of-nails as required, and verify that such current can be seen on the other appropriate contact points. A "short" on a board would be a solid connection where there should be no connection. An "open" is between two points that should be connected and are not. For small- or medium-volume boards, flying-probe and flying-grid testers use moving test heads to make contact with the copper/silver/gold/solder lands or holes to verify the electrical connectivity of the board under test |
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| luoxiaosang | Jul 25 2010, 05:23 PM Post #8 |
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Maggie Simpson
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Penelope rappelz rupees,Trunk knows something about risk. A nationally syndicated columnist, Ms. Trunk shocked the business community when she revealed intimate details of her personal life on her blog. At the time, many weren't sure this was the right move, but the blog shot up in popularity and eventually garnered over 30,000 rappelz rupees subscribers. If not for world of warcraft gold, that loyal following, Ms. Trunk might not have been able to make a case for her current venture, Brazen Careerist (BrazenCareerist.com), an online professional network for Generation Y. Launching a new company is a perilous endeavor, but Ms. Trunk thought the risk was worth it. 'This world isn't set up for writers to get anywhere,' she says. 'Although I went into massive debt and ended up sacrificing my marriage, it was essential that I take my career into world of warcraft gold my own hands.' As a result, she maple story power leveling,is no longer dependent on publications for her livelihood and has achieved one of her lifetime goals -- to serve as a mentor to twenty-something employees. Big Risks, Big Rewards If you think about it, most accomplished people in our culture are entrepreneurs who have taken big risks to net proportionally high rewards. Tough as it is for cautious people like me to accept, if you don't occasionally take calculated gambles, you won't get ahead as quickly as those who do. You will also never get over your fear of the unknown, and life will be predictable and aple story power leveling dull. How do you world of warcraft gold,go about deciding if a career risk is necessary and will bear fruit? First, it helps to think long term. Where do you want your career to be in five years, and what actions will you have to take to make sure you get there? Next, clearly define the challenge and the opportunity -- or the upside if the risk goes well. Then, consider the downside. Will the worst-case scenario be career-ending, or something that can be world of warcraft gold overcome? What's Yourworld of warcraft gold, Backup Plan? Finally, what are some clues to assess if the risk is going bad, and what is your backup plan if your risk isn't successful?In thinking through these questions, you might determine, for example, that quitting your well-paying job and spending your savings to pursue an invention idea isn't a risk you find tolerable. The smartest risks have a limited downside and a huge upside. They involve research and the counsel of experienced people -- but also the willingness to step back and let the cards fall where they world of warcraft gold may. Believe that Atlantica gold, you've made the right choice, and have faith that everything will turn out all right in the end. Insecurity and negativity won't serve you well, because you'll be constantly holding your breath, waiting for things to fall apart. Speaking of which, if a risk doesn't work out, don't let it stop you from taking similar actions in the future. It's normal to feel disappointment and even embarrassment. But it's essential that you pick yourself up and move on. Take stock of what went wrong and make a note to do it differently next time. There is no shorter path to career Atlantica gold fulfillment. |
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4:33 PM Jul 10